Saturday Update on Clipper and Snowfall Accumulation Potential

Happy Saturday to all! I have to say that I this winter so far feels like “Pittsburgh” minus the snow.  I don’t remember so many cloudy days in recent winters and I would like some snow pack and sunshine which brightens everything up.  Well those of us who want snow (it is winter after all) may have a lot to look forward to this week and into next weekend. I will address next weekend’s potential storm in another post, so let’s take a look at potential impacts to our “wonderful” Washington Area rush hour on Monday morning.

This morning’s latest (12z/7AM EST) high-resolution North American Model (NAM) is currently depicting an area of light to moderate snow impacting parts of the Washington Area between midnight and 5AM on Monday.  

0129db58-9b0b-4bc0-8e4b-86da77398b49

Where exactly this “area” of snow sets up is still in question according to the ensembles.  From what I am seeing, locations that are lucky enough to be under this area of light to moderate snow will probably pick up enough to whiten the ugly, barren, ground and if some enhanced lift occurs, don’t be surprised if some of us end up with up to an inch of snow.

  • The GFS (Global Forecast System, an American forecast model) and European ensembles (models that show variation in potential outcomes) do not fully agree on the exact track of this disturbance.

 

  • The area of best lift under this short-wave (a ripple of energy in the upper levels of the atmosphere) is not very large some of you will wake up with a coating and others nothing. Again, this is as I said going to be a conversational snow event that could impact the morning rush hour.

 

  • The National Weather Service may have to issue a Winter Weather Advisory due to our region’s rule of issuing an advisory for “one inch of snow during rush hour”. Temperatures will certainly aid in any accumulation (image below from the North American Model showing temperatures at or below freezing at 7AM Monday). 

hires_t2m_washdc_49

Here are the latest Ensembles (courtesy Wxbell.com):

  • The GEFS (Global Ensemble Forecast System) image below is not a high-resolution model so I am more so utilizing it to look for any consistency on where the band of snow develops. 
  • Bottom Line – notice how some of the ensemble members below show the coating of snow falling just south of DC, over the Metro and a minority of members keeping it north of the city.

gefs_snow_ens_washdc_11

Next up the European Ensembles (this model has been very consistent as has the Canadian):

  • The European Ensembles below do in fact show the potential band of accumulation occurring north, near or south of DC, so those of you in northern Maryland… there’s still a possibility that you may actually see some light snow with this.  If we blend the Euro and the GFS, the immediate Washington DC Metropolitan Area may just see the best lift and be the prime recipient of the accumulating snow.

eps_snow_25_washdc_13 eps_snow_50_washdc_13

Moving on to the “Operational Models”. The operational models run every few hours and input variables are not tweaked (hint:  take them with a grain of salt until tomorrow morning):

  • My favorite model (the European – aka the model with the most funding): A coating to 1.5″ of snow is the current thinking (take it with a grain of salt… while I love the European model, it is not always correct).

eps_snow_c_washdc_13

The Canadian Operational Model (aka the GEM):

cmc_snow_acc_washdc_12

To review the main points of this post based upon the latest data:

 

  • Light Snow or flurries are likely across portions of the DC Metropolitan Region Sunday night (Midnight) through the first half of the Monday morning rush hour.

 

  • Exactly where the band of steady snow develops is still in question.

 

  • A coating (few hundredths) to one inch of accumulation is possible with “jackpot” totals potentially reaching just over an inch.

 

  • This is not a widespread plowable snow, but untreated roadways will be slick in locations that receive the period of snow.

 

  • Delays are possible on Monday morning

 

One thought on “Saturday Update on Clipper and Snowfall Accumulation Potential

  1. Brendan

    While this clipper right now looks very disorganized, I have seen several of these type system with more lift than expected (most notably January 6, 2015 when several inches fell from a clipper only projected to bring around an inch). Just throwing this out there because as you saw, the models didn’t know where the most lift would be. With these ministure-starved systems, lift inthe upper atmosphere makes or breaks the storms. Any post on the storm next weekend or do you not want to say anything more than what you just said because we’ve gotten nothing so far?

    Like

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